第一种@ConfigurationProperties

• 配置文件内容

spring:
  datasource:
    druid:
      driver-class-name: com.mysql.jdbc.Driver
      password: 111111
      url: jdbc:mysql://localhost:3306/test
      username: root

• Java代码

//取配置文件中spring.datasource.druid下的内容
@ConfigurationProperties(prefix = "spring.datasource.druid")
@Component
public class DatasourcePro {

    private String url;

    private String username;

    private String password;

    // 配置文件中是driver-class-name, 横杠会自动转换成驼峰
    private String driverClassName;

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getDriverClassName() {
        return driverClassName;
    }

    public void setDriverClassName(String driverClassName) {
        this.driverClassName = driverClassName;
    }
}

• 使用方法

@RestController
@RequestMapping(value = "/config")
public class ConfigurationPropertiesController {

    @Autowired
    private DatasourcePro datasourcePro;

    @RequestMapping("/getConfig")
    public Map<String, Object> test(){

        Map<String, Object> map = new HashMap<>();
        map.put("url", datasourcePro.getUrl());
        map.put("userName", datasourcePro.getUsername());
        map.put("password", datasourcePro.getPassword());
        map.put("className", datasourcePro.getDriverClassName());

        return map;
    }
}

第二种@Value

• 配置文件内容

spring:
  datasource:
    druid:
      driver-class-name: com.mysql.jdbc.Driver

• Java代码

@Component
public class DatasourcePro {

    @Value("${spring.datasource.druid.driver-class-name}")
    private String driverClassName;

}

总结

@ConfigurationProperties支持批量注入配置文件中的属性，如果配置文件中值多的话，可以专门编写一个JavaBean来进行映射。如果只有单个值的话，就可以使用@Value。